Signaling by electromagnetic waves.



R'. A. PESSENDEN.

SIGNALING BY BLEGTROMAGNETIG WAVES. APPLICATION FILED AUG. s. 1903.

1,002,049.` PatentedAugzQ, 1911.

Jp Y nesss: t JzVEUZmW UNITED sratrnsrarianr onirica.

Vniier1ivii1.i; A. rEssENDEN, or iioiafrnnss MONROE..vineimmassieivon, BY Dinner AND MESNE ASSIGNMENTS, TO THE NATIONAL' ELECTBIG SIGNALING COMPANY, F PITTSBURG, PENNSYLYANIA, A CORPORA1ION- 0F NEW` i siGNALriivG BY ELiicTnoMAeNnfric WAv'Es.

specification tieners Patent. Patented Aug, 29, 1911, l Application'-aiedaugust' s, isos. serial iio. 168:79?.

To all whom "it may concern:

DEN, residing at Fortress Monroeyin the- 'county of Elizabeth City and State of Virginia, a citizen of the United States, have invented or discovered certa-.in new and'usefulv Improvements in Signaling by Electro-4 magnetic Waves, of which improvements the following is a specification. A y

My invention relates to .selective signaling in systems where the signal is transmit-` ted by impulses or' waves, and its primary object is to neutralize any disturbing iin-` aref-grounded. Figs.. 3 and Ltare diagrampulses or waves, that is any not having the periodicityl of those waves or impulses .which it is desired to receive. l

Figure 14 in theaccompanying vdrawing forming a part of lthis.specification shows a diagrammatic view ofa form of apparatus adapted to 'i the practice'4 of my invention. Fig. 2 shows a similar view where the aerialsI matic views illustrating modifications of my improvement. u

In the 'practice of myI invention I employ tw'o or more conductors 6 and 7, whichare tuned to different periodicities by anyk suitable means, as by the wires or coils 8 and 9,

which connect the conductors to a coherer 10 or other suitable .wave responsivev device. Each of the wires orcoils 8.and 9 is preferably of approximately the same length as the conductor to which it isconnected.

A grounding of the receiving conductors is not necessary, as eiiicient receiving can be Y eected. without a ground. A suitable construction where a ground is used is shown' in Fig. 2, where `6 and 7 are the aerials, 8 and 9 primaries of transformers, whose secondaries 16 and `17 are arranged to act upon the receiver'v 10.. A condenser 13. mayv be used as shown.

Whenfemploying'a coherer. it is connectedN as usual in the circuit o f a battery 11, 1, or 1, Fig. 2, and with a relay or transmit. ting mechanism,` 12, 1, or 15,-Fig. 2. In'the construction here shown the wave responsive device is affected by waves of either of the periodicities to .which the receivingconductors 6 and'7 are tuned, or to both periodicities conjintly, provided that the oscillations are suciently prolonged. The wave' responsive device may be adJusted by varying its sensibility so as to respondi mined degree.

-a frequency diiferent from thatwhich it desired to receive produced by other. sta- QA tions or by atmospheric disturbances willbe only when .the effect of vboth the aerials is Be it known that LREoiNALD A. FEssENf Y added and not to the effect produced by a single one, in which case the Wave responsive device will only be operated by the con- ]oint action of the two sets of waves.

When an electric impulse is received by the conductors 6 and 7, the rst few oscil1ations of the seriesof Waves will generate tential fat oneu end of the coherer will rise higher than that of the other and the receiver Awill be actuated. If, however, the periodicity of the impulser does not agree with thatn to which either receiving conducltor is t-uned, there Will be no cumulative rise in the potential at one end of the receiving device, andif the periodicity of the impulse bte sufficiently different from the` periodicitiesto which .the receiving conductors are timed, there willv be no appreciable rise at one end above that of the opposite end.

. As the coherer or other translating device is so constructed as to be unresponsive to aplproximately'f equal potentials, or the poten-v ltials so nearly neutralize each other as to produce no operative effect on the coherer or Wave responsive device, it follows that 4 the 'apparatus at any receiving station will not respond to any wave .or series of'waves or impulses which will not produce or generate .at the coheier or other wave' responsive device potentials differing to a predeter- Thus disturbing impulses of unable to affect the receiver.

It is preferred that the aerials. 6 and 7 should be of approximately the same height, z'. e., should not diifer more thania f ew per cent.

AWhere this invention is used for wire lines,a's telegraph lines or cables, the conductors 6 and 7 are preferably connected to each other above the coils 8, 9, and the junction connected to the line YWire '14, as shown inV Fig. 3. 'In this case condensers 13 are preferably placed in series `with each,

of the conductors'6 and 7'also, instead lof grounding the conductors and 7, they' may" .nearly the same potential at the ends of the -coherer or translating device 10, Fig. l. But if the oscillations persist', and their periodicity agrees with that .to which either vof the receiving conductors is timed, the l'po- .be connected to a return conductor. In-

-"stead of a coherer a cuinulatively acting receiver, of the current' operated type, as a barretter is; preferably used,

By receiving conductor I mean the entire 4circuit including the antenna and to ground.

What I claim as my invention: i l. In a system `of signaling, a 4conductor for leading the'i'eceived impulses into the .receiving stationgtwo circuit'elexnents opervvatively connected "to said eonductor, and a circuit containing a receiver, operatively connected to said circuit'.l elements in such a manner that said circuit elements produce volta-ges Vapproi'cim'ately equal but opposite in signin the circuit containing the receiver, onthe receipt of disturbing impulses, and voltages differing in magnitude on the receipt oflhefdesired impulses.

l 2. In a system of signaling, a conductor, t foi'-1eadiiig the received impulses mtotlie V'{nitudc ontlie receipt of the desired im-v y pulses."

3.'In afs'ign'aling system,a conductor for leading the received impulses into the receiving'v station; two transformers having their primaries connected to the leading in conductor, and a receiver opera-tively con,-`

nected to the secondaries of the transformers.

4. In a system of signaling by periodic 40 impulses a conductor for Vleading received impulses into the receiving station, two transformers having ltheir primaries in parallel with each other and operatively connected to the leading in conductor and a condenser .in series with each of the .primaries of the transformers, and the secondaries of the transformers opera-tively c'onnected to eachother and to a receiver, in

suoli' a manner that they oppose and neutral.- 50

ize the effect on the receiver o-f disturbing impulses, while the elfeet of impulses of the desired frequency is transmitted to the re-,Q ceiver in practicallyefull strength;

5. In a system of wireless'signaling, the 55` combination of an antenna, a` receiver and two circuits having suitable electric com'. 'stants and'suitably arranged to neutralize the effect on the receiver of disturbing inipulses received from any direction.

6. The combinationl of two antennae of approximately equal height butl of different natural periods, a circuit containing a' receiver inductively, connected with both antennae and arranged to be responsive onlyV to a particular frequency of waves received on the said antennae, substantially -as' described.l e V In 'testimony whereof, I have hereto set.

my hand. I v n' REGINALDA. FESSENDEN. o

W'itnessesl DARWIN S. IVoLoo'r'r,

vIVM. H. DE LACY. 

